摘要：為回調函數等于已過時間初始值距離總時間勻速加速曲線減速曲線加速減速曲線加加速曲線減減速曲線加加速減減速曲線正弦衰減曲線彈動漸入正弦增強曲線彈動漸出回退加速回退漸入回縮的距離彈球減振彈球漸出

function doMove(obj, json, time, fx, fn) //fn為回調函數
{

clearInterval(obj.iTimer);

var fx = fx || "linear";

var d = time || 1000;

var j = {}

for (var attr in json) {

    j[attr] = {};

    if (attr == "opacity") {

        j[attr].b = Math.round(css(obj, attr) * 100);

    } else {

        j[attr].b = parseInt(css(obj, attr));

    }

    j[attr].c = json[attr] - j[attr].b;
}

var t1 = +new Date(); //等于new Date().getTime();

obj.iTimer = setInterval(function() {

    var t = +new Date() - t1;

    if (t >= d) {

        t = d;
    }

    for (var attr in json) {

        var v = Tween[fx](t, j[attr].b, j[attr].c, d);

        if (attr == "opacity") {

            obj.style.opacity = v / 100;

            obj.style.filter = "alpha(opacity="+v+")";

        } else {

            obj.style[attr] = v + "px";
        }
    }

    if (t == d) {

        clearInterval(obj.iTimer);

        fn && fn();
    }

}, 30);

}

function css(obj, attr)
{

if (obj.currentStyle) {

    return obj.currentStyle[attr];

} else {

    return getComputedStyle(obj, false)[attr];

}

}

var Tween = //t : 已過時間; b : 初始值; c : 距離; d : 總時間

{

linear: function (t, b, c, d){  //勻速

    return c*t/d + b;

},

easeIn: function(t, b, c, d){  //加速曲線

    return c*(t/=d)*t + b;

},

easeOut: function(t, b, c, d){  //減速曲線

    return -c *(t/=d)*(t-2) + b;

},

easeBoth: function(t, b, c, d){  //加速減速曲線

    if ((t/=d/2) < 1) {

        return c/2*t*t + b;

    }

    return -c/2 * ((--t)*(t-2) - 1) + b;

},

easeInStrong: function(t, b, c, d){  //加加速曲線

    return c*(t/=d)*t*t*t + b;

},

easeOutStrong: function(t, b, c, d){  //減減速曲線

    return -c * ((t=t/d-1)*t*t*t - 1) + b;

},

easeBothStrong: function(t, b, c, d){  //加加速減減速曲線

    if ((t/=d/2) < 1) {

        return c/2*t*t*t*t + b;

    }

    return -c/2 * ((t-=2)*t*t*t - 2) + b;

},

elasticIn: function(t, b, c, d, a, p){  //正弦衰減曲線（彈動漸入）

    if (t === 0) { 

        return b; 

    }

    if ( (t /= d) == 1 ) {

        return b+c; 

    }

    if (!p) {

        p=d*0.3; 

    }

    if (!a || a < Math.abs(c)) {

        a = c; 

        var s = p/4;

    } else {

        var s = p/(2*Math.PI) * Math.asin (c/a);

    }

    return -(a*Math.pow(2,10*(t-=1)) * Math.sin( (t*d-s)*(2*Math.PI)/p )) + b;

},

elasticOut: function(t, b, c, d, a, p){    //正弦增強曲線（彈動漸出）

    if (t === 0) {

        return b;

    }

    if ( (t /= d) == 1 ) {

        return b+c;

    }

    if (!p) {

        p=d*0.3;

    }

    if (!a || a < Math.abs(c)) {

        a = c;

        var s = p / 4;

    } else {

        var s = p/(2*Math.PI) * Math.asin (c/a);

    }

    return a*Math.pow(2,-10*t) * Math.sin( (t*d-s)*(2*Math.PI)/p ) + c + b;
},    

elasticBoth: function(t, b, c, d, a, p){

    if (t === 0) {

        return b;

    }

    if ( (t /= d/2) == 2 ) {

        return b+c;

    }

    if (!p) {

        p = d*(0.3*1.5);

    }

    if ( !a || a < Math.abs(c) ) {

        a = c; 

        var s = p/4;

    }else {

        var s = p/(2*Math.PI) * Math.asin (c/a);

    }

    if (t < 1) {

        return - 0.5*(a*Math.pow(2,10*(t-=1)) * 
                Math.sin( (t*d-s)*(2*Math.PI)/p )) + b;

    }

    return a*Math.pow(2,-10*(t-=1)) * 
            Math.sin( (t*d-s)*(2*Math.PI)/p )*0.5 + c + b;

},

backIn: function(t, b, c, d, s){     //回退加速（回退漸入）

    if (typeof s == "undefined") {

       s = 1.70158;

    }

    return c*(t/=d)*t*((s+1)*t - s) + b;

},

backOut: function(t, b, c, d, s){

    if (typeof s == "undefined") {

        s = 3.70158;  //回縮的距離

    }

    return c*((t=t/d-1)*t*((s+1)*t + s) + 1) + b;

}, 

backBoth: function(t, b, c, d, s){

    if (typeof s == "undefined") {

        s = 1.70158; 

    }

    if ((t /= d/2 ) < 1) {

        return c/2*(t*t*(((s*=(1.525))+1)*t - s)) + b;

    }

    return c/2*((t-=2)*t*(((s*=(1.525))+1)*t + s) + 2) + b;

},

bounceIn: function(t, b, c, d){    //彈球減振（彈球漸出）

    return c - Tween["bounceOut"](d-t, 0, c, d) + b;

},    

bounceOut: function(t, b, c, d){

    if ((t/=d) < (1/2.75)) {

        return c*(7.5625*t*t) + b;

    } else if (t < (2/2.75)) {

        return c*(7.5625*(t-=(1.5/2.75))*t + 0.75) + b;

    } else if (t < (2.5/2.75)) {

        return c*(7.5625*(t-=(2.25/2.75))*t + 0.9375) + b;

    }

    return c*(7.5625*(t-=(2.625/2.75))*t + 0.984375) + b;

},      

bounceBoth: function(t, b, c, d){

    if (t < d/2) {

        return Tween["bounceIn"](t*2, 0, c, d) * 0.5 + b;

    }

    return Tween["bounceOut"](t*2-d, 0, c, d) * 0.5 + c*0.5 + b;

}

}